I am a Professor in the Departments of Earth and Planetary Science and Environmental Science, Policy, and Management (see contact information below). I also have an appointment in the geochemistry group at Lawrence Berkeley National Laboratory. My primary research interests are in geomicrobiology and environmental microbiology. My group studies how microorganisms shape, and are shaped by, their natural environments. My research group studies microbial communities, primarily using cultivation-independent approaches such as genomics (metagenomics) and community proteomics. We work on microbial dissolution and precipitation of minerals, the structure, properties, and reactivity of nanoparticles (many of which are formed by microorganisms), microbial ecology, and microbial evolution. Virtually all of our projects are tied to a field site. Current locations of study are Iron Mountain (northern California), the Angelo Reserve (northern California), the Rifle and East River sites, Colorado, Crystal Geyser, Utah

In my research group we study microbial communities - the organisms present and the ways in which they interact with, and shape their environments.

We develop bioinformatics-based methods that allow us to explore the diversity of orgnaisms in Earth's environments using DNA sequencing and other "omics" and geochemical data. Our approach centers around the reconstruction of genomes for the organisms present and analysis of the capacities of these organisms and their impacts on their environments.

We also study shale weathering, clay minerals, and microbial processes in riparian zone sediments, soils, and the deeper subsurface.